Epidemiologic studies are conducted to identify life-style and environmental risk factors for cancer and to investigate their interrelationships with genetic determinants of these diseases. Case-control studies of cancers of the bladder, prostate, pancreas, esophagus, stomach, lung, brain, and head and neck, as well as non-Hodgkins lymphoma and multiple myeloma, are in progress. A large case-control study of bladder cancer is progressing in Spain to identify occupational bladder carcinogens and to evaluate non-occupational exposures including cigarette smoking (black vs. blond tobacco), phenacetin-containing analgesics, dietary factors, and urination frequency and pH. Genetic susceptibility markers also will be evaluated in relation to bladder cancer risk, as well as their interaction with epidemiologic risk factors. A large multi-center investigation is examining risk factors for malignant neoplasms among subjects being screened for cancers of the prostate, lung, colon, rectum, and ovaries. A feasibility study for a large case-control study of bladder cancer in New England is underway to determine the reasons for the persistently elevated bladder cancer mortality and incidence in the northeastern United States. In a case-control study of pancreatic cancer conducted to determine the reasons for the black excess in risk of the disease, established risk factors (mainly cigarette smoking and diabetes mellitus) explained almost the entire black/white disparity in incidence among men. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption and elevated body mass index. Results from a case-control study of multiple myeloma suggested that socioeconomic status-related variables (i.e., income, education, and occupation) account for a substantial proportion of the black/white differential in multiple myeloma incidence. In a case-control study of lung cancer in Missouri women, the heterocyclic amine, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), which is found in meats cooked at high temperatures, was associated with increased lung cancer risk. Data from a case-control study of lung cancer in Iowa women suggested that consumption of red meat was associated with an increased risk of lung cancer even after adjustment for total fat, saturated fat, cholesterol, yellow-green vegetable consumption and smoking history. In Mexico, a case-control study of gastric cancer found that elevated intake of polyunsaturated fat, fiber, and vitamin E reduced gastric cancer risk. In Taiwan, a case-control study of nasopharyngeal cancer found that dietary nitrosamine and nitrate intake in childhood may play a role in the development of this malignancy.